11 replies to this topic

[Minitrio]

Hi everyone,

Just completed fitting a stage 1 kit to my 89 998, took it out for a run and it pulls away nicely and does everything it should, except on slow deacceleration.

Basically if you take your foot off the accelerator and let her slow without braking, revs drop to 2200rpm and the engine starts violently vibrating, making the whole car shake, not stutter as if she was about to stall. If you change down, from 4th to 3rd it stops, if you accelerate again it stops. Also if you rapidly deaccelerate using the brake it doesn't do it. Another thing I have noticed is she starts first time and idles at around 850-900rpm, but when warmed up she will idle at junctions at 1200-1400rpm (it not consistently the same at each junction)

I have changed the top engine steady bushes for poly bushes, so there new. I have got some new engine mounts to fit, but I think it's the way the engine is running, rather than mounts, because it only does it at a set rpm rather than all the time.

Anyone any pointers as to what may cause this?

I will be getting her roller road tuned, once I find one that's a little mini savvy. Just need to sort this vibration out in the short term

Thanks for reading.

[Minitrio]

I'm glad your all baffled too...

[David128]

some things take a while.... could be diff or inboard pot joint.or something totally out  there Its one of those that you really need to be there ..sorry cant help more

[Coxie]

Have you set the mixture up correctly after changing the needle and air filter.
Mine will do this on decelleration when running way too rich.

[jaydee]

Way too rich and idle speed too high

Probably wrong ignition timing aswell..

[Minitrio]

Thanks guys, having done a few runs now, the mixture appears to be too rich.

Never done timing on a mini before, I have done an aircooled vdub, which was mainly done by ear.

Would the timing be set by the figures for a Standard 998 or the Hif 38 carb?

Will also reset the carb and start again as advised by Burlens SU workshop manual.

[jaydee]

Set static timing in the middle between the 4 and 8 deg marks on the timing cover, then you can go 'by ear' advancing till you get pinking at 2000-2500 rpm then a couple degrees back.

It wont be the ultimate tuning, but the results are decent enough to run your mini before having it rolling roaded.

[Minitrio]

Thanks so far guys, a little update.

Re adjusted the carb, mixture was way to rich, now idling well. Choke cable was also a little tight, so adjusted also.

As for the vibration, I carried out several 5 mile runs and tried varies things, it now appears to be coming from braking from 60 down to 30mph, emergency breaking doesn't cause any just pulls to the left slightly and gradual braking from roughly 30 - 10/0mph doesnt show any vibration. I can only feel it when braking at speed, which transmits through the steering wheel and slightly through the brake pedal.

So I'm kind of thinking this is a brake disc, pad or both issue, but surely I would feel this during all braking...wouldn't I?

[jaydee]

So you have some sort of brake judder, and could be due a Cv joint-wheel bearing-drive flange assembly issue

First thing to do is to check balljoints for play and check the disc run out with a DTI, when the run out is over 6 thou your discs are unevenly worn (some say 'warped' although its not actually the correct term). This is usually caused by a problem in the Cv joint-wheel bearing-drive flange assembly and simply replacing the discs wont cure it. Also a sticking caliper piston can give the same issues.

[myredmini]

For best results a rolling road session is required after fitting a "stage 1 kit". You wont regret it!

[Minitrio]

Thanks guys, apologise for the late response.

Plan to check the ball joints and CV joints prior to the brakes this weekend, weather dependant....not looking good!

Then hopefully when the suspension rubbers have settled fully, everything should be sorted

[pusb]

Check the exhaust for the vibration. Mine was knocking the floor on deceleration, but it took me a while to find what it was.